Immediately after the killing it was reasonable to assume that Elizabeth Barraza's husband was the most likely suspect.
In October 2022 Paula Zahn aired an episode which changed things though.
As of March 2023 below is the most likely sequence of events surrounding the murder of Elizabeth Barraza.
January 2017 to January 2019
Elizabeth Barraza's father in law had a flooring business which doubled as a way for him to meet women.
Within approximately this 2 year window one of the jobs he went on involved a household with an overprotective father living with a rebellious daughter. On the day in question Elizabeth Barraza's father in law arrived at the job, and the daughter at that house was angry at the limits placed by her father. She flirted with the flooring contractor, he responded enthusiastically, and they had a brief 'relationship'.
Days or weeks later the girl's father was hemming her in so she played her card. Something like "Daddy you can't control me, I did that flooring contractor".
The girl's father verified, to his satisfaction, that the girl was telling the truth.
He then contacted a person he trusted thoroughly, probably a childhood friend in southern Mexico, and probably in direct conversation during a trip to Mexico, and discussed punitive action.
December 2018 through January 2019
Aware of the risks of killing on U.S. soil, and after careful consideration of options, the decision is made to target the wife of the flooring contractor's son. A person was placed in the area to get information, and in late January 2019 they decide to move.
January 24 to January 26, 2019
A shooter and his assistant drive north and cross from Mexico into Texas using fake documents.
The goal is to kidnap the wife of the offender's son, but the person is selected for his willingness to kill if he feels it is necessary, not for his kidnapping skills.
January 26, 2019
License plates on the vehicle are swapped with stolen/temporary plates and the kidnapping proceeds, but goes awry when she refuses to walk with the kidnapper back to his truck, and he kills her.
License plates are switched back and the killer crosses back into Mexico.
January 26 to early February, 2019
Local police ask for help from federal agencies.
People at a federal agency quickly realize that the shooter is not a 'U.S. person', and that there has been no chatter about the hit among groups they monitor.
The vehicle is identified from film at a border crossing, and a U.S. agency watches the shooter's communications for a while before determining he and his close colleagues are independent of any network that agency had been monitoring.
Because this group is so small it could effectively be eliminated by arresting the people identified within the first few weeks, but the federal agents involved are led by supervisors who are 'long term corrupt' government agents in the style of Felix Rodriguez and his crew. They decide to empower the group by penetrating it and feeding them information that will help them grow under their control.
Felix Rodriguez was a CIA agent who imported cocaine and other drugs into the United States for 'power and profit', but operated under cover of acting on national security. U.S. federal law enforcement has been aware of the activities of Rodriguez and dozens of similar agents for decades, but are afraid/powerless to arrest them. Despite numerous murders, including the high profile killing of Kiki Camarena in the 1980s, this network of U.S. federal agents operates with impunity and has the full resources of the U.S. government at their disposal.
The corrupt federal agents know they have to create a smokescreen to throw investigators off the trail of their budding new mini cartel so they start creating diversions.
In order to distract from the obvious 'kidnapping' scenario, since the shooter extended his arm just before shooting, they start a story that maybe he handed her a note. Most U.S. people have no idea that kidnappings are common in many countries so the story is unchallenged by media and public.
When the family of the victim starts pushing police as to why no progress has been made, a story is invented about a possible tip in Miami. That will keep local police busy for a few days and give the appearance that federal agents are still working to solve the case.
What can be reasonably guessed about the shooter?
Male in his early 20s from Guatemala/Mexico border area.
OCD, prefers to work alone but is comfortable with people from that area.
Raised in a rural area.
How likely is the timeline above?
~90% based only on the information so far.
Why are Texas authorities not clarifying various facts about the case even after it is unsolved for four years?
The federal authorities who are cultivating the killer and his circle will provide an endless list of reasons to Texas authorities for why certain details are not released.
They have probably used their knowledge of the killer's network to merge it with another network they have influence over, and they have to be careful that the public does not find out how those networks are used. There have been many similar scandals, the gunwalking scandal, Iran Contra murder of Kiki Camerena, and many others. Most never become public, but the southern U.S. border is probably the epicenter of U.S. law enforcement misconduct.
Would the person who started the story about the shooter handing her a note have some connection to the border agents or other law enforcement trying to keep the case unsolved?
Would the federal agents who arranged the Miami distraction be a few steps or less from the federal agents behind the ruse?
Is there some chance that the ruse really is designed to reduce some sort of crime or otherwise serve the public interest?
No, it's clear what they are doing and why, and their ambition is not related to anything that is intended to help anybody other than themselves.
A few seconds after Elizabeth says 'Good morning' the shooter seems to say 'morning' as a fair English speaker, isn't it possible the shooter is from Texas?
Is it more likely the woman who triggered the plot was daughter or girlfriend/wife of the person who arranged it?
The scenario listed is daughter, but actually girlfriend/wife is more likely.
A person targeting somebody who offended an over protected daughter would be targeted more directly usually.
A wife or girlfriend in a situation like that would be more like 'property' though to somebody who would retaliate indirectly that way.
So the fact that Elizabeth was targeted, and not Oscar or Sergio makes it a little more likely the woman was wife/girlfriend rather than daughter.